You can present your design thinking via walking through work you've already done with a team, real business challenges, and results. It's like somehow talking about your body of work uis less valuable than a ridiculous assignment that doesn't simulate the real world at all. I think it's because the people they assign to the interview team have no actual clue what good UX work is, so they have no idea what to ask a candidate about their work. So they come up with an "assignment" that they imagine levels the playing field for everyone.

I've been put through a couple of these, and the result was: the person assigning the homework had a different idea of what the deliverable was than the rest of the folks in the interview process. I thought I was doing UX, the others were expecting polished UI. After two of these fiascos, I no longer continued my candidacy. I did end up getting the job I have now, no homework, just a review of my work in a discussion.